All writers should be keen observers of the human condition. If you are to write convincingly, then you must be able to connect with readers at a variety of levels. I try to view everything in my life around the phrase, "How would I write that?"
Case in point: I work in the construction equipment rental industry and while loading a customer's personal truck I caused a scratch in his paint. I was basically goofing around and swinging myself down on some other piece of equipment. It was uneccessary and frankly a bit embarrassing. The customer's reaction is the lesson here. He starts in with semi-smart alec comments about what kind of discount he's going to get on what he's renting and who he should send the bill to for a new paint job. (Never mind that this is a work truck and is bound to rack up several scratches a year. You should see my F150.) The writing lesson is how to present his reactions. There was something in the way he held up and waited for a response that really aggravated me and made the whole situation very uncomfortable. I'm clearly in the wrong but there's no way I'm offering to pay for anything. I think this customer is just the type that likes to get one up on someone and then enjoy watching them twist in the wind, i.e. he's a jerk.
So do you write this from the outside and just describe the way he laughs and asks about new paint? Or do you write an internal reaction from my perspective and get into a character's thoughts? Which way would be faster? Which way would be clearer?
The great thing about these questions is that they have no correct answers. They all depend on the situation and the goal of the author. But this is the sort of thing I look for in life.